ABSTRACT
In 1986, Bednorz and Miiller at IBM Zurich Research Laboratory discovered a new outstanding superconductor with a critical temperature, Tc, of 30 K in the La-Ba-Cu-0 (LBCO) system [(La, Ba)2Cu04] [1]. The discovery led Tanaka's group at the University of Tokyo to interest in the new higher Tc than that could be predicable from the classic BardeenCooper-Schrieffer (BCS) theory. Late in 1986, they demonstrated that the substitution of Sr for Ba worked to increase Tc as high as 42.5 K [2]. Once their results were announced (in December 1986), many challenges were started to find oxides with even higher Tc. Very soon after, the Tc in the La oxide series reached the maximum of 57 K only under a high pressure of 12kbars [3].
